1. Field of the Invention
This invention relates to improved soap-based lubricants, more particularly, chain conveyor lubricants and even more particularly, to aqueous compositions for such application containing fatty acid soaps.
2. Description of the Prior Art
In breweries, soft drink bottling operations and food processing plants, conveyors are used to move the bottles, jars, cans, and the like along the line. In order to keep the conveyor chains clean and provide lubrication, it is customary to use a lubricant such as an aqueous soap-based lubricant. These compositions also include chelating agents to prevent precipitation of calcium and magnesium soaps. These lubricants are generally manufactured and sold as concentrates which must then be diluted to in general about 1:100 with tap water at the point of use. However, prior to dilution, the concentrate is fed through proportioning pumps or injectors whereby it is important that the concentrated soaps which tend to be very viscous have their viscosity reduced. In the prior art, materials have been added to reduce viscosity of the concentrated lubricants, more particularly, propylene glycol, isopropyl alcohol, capric (decanoic) acid and coconut fatty acid. Also, some surfactants such as alkoxylated alcohols have been employed to reduce viscosity. However, antifreezes such as propylene glycol and isopropyl alcohol, while they may reduce viscosity to some extent, also may reduce lubricity. Natural materials such as capric (decanoic) acid and coconut fatty acid may reduce viscosity but lubricity is slightly reduced and they often require more chelating agents to handle the additional precipitates when diluted with normal tap water. Further, lubricants which contain capric or coconut fatty acid tend to cause an objectionable black film on the bottoms of the bottles and other containers passing along the conveyor. The surfactants generally have the disadvantages of higher costs, and an excess of surfactant sometimes cleans the metal surface to a point where lubricity may be lost completely.
Accordingly, it is the purpose of this invention to provide an aqueous soap-based lubricant particularly a lubricant for chain conveyors which has low viscosity, good lubricity, which does not blacken the bottoms of the bottles and cans or other containers when employed on conveyors and which does not require extra chelating agents to handle the additional precipitates when diluted with normal tap water.